Subclasses may reimplement initializeDefaultPreferences
to set up any default values for preferences using JFace API. In this
case, initializeDefaultPluginPreferences should not be
overridden.

Subclasses may reimplement
initializeDefaultPluginPreferences to set up any default
values for preferences using core runtime API. In this
case, initializeDefaultPreferences should not be
overridden.

Preferences are also saved automatically on plug-in shutdown.
However, saving preferences immediately after changing them is
strongly recommended, since that ensures that preference settings
are not lost even in the event of a platform crash.

Dialogs

The dialog store is read the first time getDialogSettings
is called.

The dialog store allows the plug-in to "record" important choices made
by the user in a wizard or dialog, so that the next time the
wizard/dialog is used the widgets can be defaulted to better values. A
wizard could also use it to record the last 5 values a user entered into
an editable combo - to show "recent values".

The dialog store is found in the file whose name is given by the
constant FN_DIALOG_STORE. A dialog store file is first
looked for in the plug-in's read/write state area; if not found there,
the plug-in's install directory is checked.
This allows a plug-in to ship with a read-only copy of a dialog store
file containing initial values for certain settings.

Plug-in code can call saveDialogSettings to cause settings to
be saved in the plug-in's read/write state area. A plug-in may opt to do
this each time a wizard or dialog is closed to ensure the latest
information is always safe on disk.

Dialog settings are also saved automatically on plug-in shutdown.

Images

A typical UI plug-in will have some images that are used very frequently
and so need to be cached and shared. The plug-in's image registry
provides a central place for a plug-in to store its common images.
Images managed by the registry are created lazily as needed, and will be
automatically disposed of when the plug-in shuts down. Note that the
number of registry images should be kept to a minimum since many OSs
have severe limits on the number of images that can be in memory at once.

For easy access to your plug-in object, use the singleton pattern. Declare a
static variable in your plug-in class for the singleton. Store the first
(and only) instance of the plug-in class in the singleton when it is created.
Then access the singleton when needed through a static getDefault
method.

As of Eclipse 2.0, a basic preference store exists for all
plug-ins. This method now exists only for backwards compatibility.
It is called as the plug-in's preference store is being initialized.
The plug-ins preferences are loaded from the file regardless of what
this method does.

As of Eclipse 2.0, preferences exist for all plug-ins. The
equivalent of this method is Plugin.savePluginPreferences.
This method now calls savePluginPreferences, and exists only for
backwards compatibility.

In Eclipse 3.0, shutdown has been replaced by Plugin.stop(BundleContext context).
Implementations of shutdown should be changed to extend
stop(BundleContext context) and call super.stop(context)
instead of super.shutdown(). Unlike super.shutdown(),
super.stop(context) must be called as the very last thing rather
than as the very first thing. The shutdown method is called
only for plug-ins which explicitly require the
org.eclipse.core.runtime.compatibility plug-in;
in contrast, the stop method is always called.

Constructor Detail

AbstractUIPlugin

The AbstractUIPlugin(IPluginDescriptor) constructor was called
only for plug-ins which explicitly require the
org.eclipse.core.runtime.compatibility plug-in.
It is not called anymore as Eclipse 4.6 removed this plug-in.

AbstractUIPlugin

public AbstractUIPlugin()

Creates an abstract UI plug-in runtime object.

Plug-in runtime classes are BundleActivators and so must
have an default constructor. This method is called by the runtime when
the associated bundle is being activated.

getImageRegistry

The image registry contains the images used by this plug-in that are very
frequently used and so need to be globally shared within the plug-in. Since
many OSs have a severe limit on the number of images that can be in memory at
any given time, a plug-in should only keep a small number of images in their
registry.

Subclasses should reimplement initializeImageRegistry if they have
custom graphic images to load.

Subclasses may override this method but are not expected to.

Returns:

the image registry

getPreferenceStore

Returns the preference store for this UI plug-in.
This preference store is used to hold persistent settings for this plug-in in
the context of a workbench. Some of these settings will be user controlled,
whereas others may be internal setting that are never exposed to the user.

If an error occurs reading the preference store, an empty preference store is
quietly created, initialized with defaults, and returned.

NOTE: As of Eclipse 3.1 this method is
no longer referring to the core runtime compatibility layer and so
plug-ins relying on Plugin#initializeDefaultPreferences
will have to access the compatibility layer themselves.

initializeDefaultPreferences

Initializes a preference store with default preference values
for this plug-in.

This method is called after the preference store is initially loaded
(default values are never stored in preference stores).

The default implementation of this method does nothing.
Subclasses should reimplement this method if the plug-in has any preferences.

A subclass may reimplement this method to set default values for the
preference store using JFace API. This is the older way of initializing
default values. If this method is reimplemented, do not override
initializeDefaultPluginPreferences().

The AbstractUIPlugin implementation of this
Plugin method forwards to
initializeDefaultPreferences(IPreferenceStore).

A subclass may reimplement this method to set default values for the core
runtime preference store in the standard way. This is the recommended way
to do this. The older
initializeDefaultPreferences(IPreferenceStore) method
serves a similar purpose. If this method is reimplemented, do not send
super, and do not override
initializeDefaultPreferences(IPreferenceStore).

initializeImageRegistry

Initializes an image registry with images which are frequently used by the
plugin.

The image registry contains the images used by this plug-in that are very
frequently used and so need to be globally shared within the plug-in. Since
many OSs have a severe limit on the number of images that can be in memory
at any given time, each plug-in should only keep a small number of images in
its registry.

Implementors should create a JFace image descriptor for each frequently used
image. The descriptors describe how to create/find the image should it be needed.
The image described by the descriptor is not actually allocated until someone
retrieves it.

loadDialogSettings

protected void loadDialogSettings()

Loads the dialog settings for this plug-in.
The default implementation first looks for a standard named file in the
plug-in's read/write state area; if no such file exists, the plug-in's
install directory is checked to see if one was installed with some default
settings; if no file is found in either place, a new empty dialog settings
is created. If a problem occurs, an empty settings is silently used.

This framework method may be overridden, although this is typically
unnecessary.

loadPreferenceStore

Deprecated.As of Eclipse 2.0, a basic preference store exists for all
plug-ins. This method now exists only for backwards compatibility.
It is called as the plug-in's preference store is being initialized.
The plug-ins preferences are loaded from the file regardless of what
this method does.

Loads the preference store for this plug-in.
The default implementation looks for a standard named file in the
plug-in's read/write state area. If no file is found or a problem
occurs, a new empty preference store is silently created.

This framework method may be overridden, although this is typically
unnecessary.

refreshPluginActions

protected void refreshPluginActions()

Refreshes the actions for the plugin.
This method is called from startup.

This framework method may be overridden, although this is typically
unnecessary.

saveDialogSettings

protected void saveDialogSettings()

Saves this plug-in's dialog settings.
Any problems which arise are silently ignored.

savePreferenceStore

Deprecated.As of Eclipse 2.0, preferences exist for all plug-ins. The
equivalent of this method is Plugin.savePluginPreferences.
This method now calls savePluginPreferences, and exists only for
backwards compatibility.

Saves this plug-in's preference store.
Any problems which arise are silently ignored.

shutdown

Deprecated.In Eclipse 3.0, shutdown has been replaced by Plugin.stop(BundleContext context).
Implementations of shutdown should be changed to extend
stop(BundleContext context) and call super.stop(context)
instead of super.shutdown(). Unlike super.shutdown(),
super.stop(context) must be called as the very last thing rather
than as the very first thing. The shutdown method is called
only for plug-ins which explicitly require the
org.eclipse.core.runtime.compatibility plug-in;
in contrast, the stop method is always called.

The AbstractUIPlugin implementation of this Plugin
method does nothing. Subclasses may extend this method, but must send
super first.

start

The AbstractUIPlugin implementation of this Plugin
method refreshes the plug-in actions. Subclasses may extend this method,
but must send super first.
Starts up this plug-in.

This method should be overridden in subclasses that need to do something
when this plug-in is started. Implementors should call the inherited method
at the first possible point to ensure that any system requirements can be met.

If this method throws an exception, it is taken as an indication that
plug-in initialization has failed; as a result, the plug-in will not
be activated; moreover, the plug-in will be marked as disabled and
ineligible for activation for the duration.

Note 1: This method is automatically invoked by the platform
the first time any code in the plug-in is executed.

Note 2: This method is intended to perform simple initialization
of the plug-in environment. The platform may terminate initializers
that do not complete in a timely fashion.

Note 3: The class loader typically has monitors acquired during invocation of this method. It is
strongly recommended that this method avoid synchronized blocks or other thread locking mechanisms,
as this would lead to deadlock vulnerability.

Note 4: The supplied bundle context represents the plug-in to the OSGi framework.
For security reasons, it is strongly recommended that this object should not be divulged.

Note 5: This method and the Plugin.stop(BundleContext) may be called from separate threads,
but the OSGi framework ensures that both methods will not be called simultaneously.

stop

The AbstractUIPlugin implementation of this Plugin
method saves this plug-in's preference and dialog stores and shuts down
its image registry (if they are in use). Subclasses may extend this
method, but must send super last. A try-finally statement should
be used where necessary to ensure that super.stop() is
always done.
Stops this plug-in.

This method should be re-implemented in subclasses that need to do something
when the plug-in is shut down. Implementors should call the inherited method
as late as possible to ensure that any system requirements can be met.

Plug-in shutdown code should be robust. In particular, this method
should always make an effort to shut down the plug-in. Furthermore,
the code should not assume that the plug-in was started successfully.

Note 1: If a plug-in has been automatically started, this method will be automatically
invoked by the platform when the platform is shut down.

Note 2: This method is intended to perform simple termination
of the plug-in environment. The platform may terminate invocations
that do not complete in a timely fashion.

Note 3: The supplied bundle context represents the plug-in to the OSGi framework.
For security reasons, it is strongly recommended that this object should not be divulged.

Note 4: This method and the Plugin.start(BundleContext) may be called from separate threads,
but the OSGi framework ensures that both methods will not be called simultaneously.

imageDescriptorFromPlugin

Creates and returns a new image descriptor for an image file located
within the specified plug-in.

This is a convenience method that simply locates the image file in within
the plug-in. It will now query the ISharedImages registry first. The path
is relative to the root of the plug-in, and takes into account files
coming from plug-in fragments. The path may include $arg$ elements.
However, the path must not have a leading "." or path separator. Clients
should use a path like "icons/mysample.png" rather than
"./icons/mysample.png" or "/icons/mysample.png".

Parameters:

pluginId - the id of the plug-in containing the image file;
null is returned if the plug-in does not exist

imageFilePath - the relative path of the image file, relative to the root of
the plug-in; the path must be legal